Perceived stress and stress responses during COVID-19: The multiple mediating roles of coping style and resilience

Although many studies have examined the effects of perceived stress on some specific stress responses during the COVID-19, a comprehensive study is still lacking. And the co-mediating role of coping style and resilience as important mediators of stress processes is also unclear. This study aimed to explore the effects of perceived stress on emotional, physical, and behavioral stress responses and the mediating roles of coping style and resilience in Chinese population during the recurrent outbreak of COVID-19 from a comprehensive perspective. 1087 participants were recruited to complete the anonymous online survey including the Perceived Stress Scale, the Stress Response Questionnaire, the Simplified Coping Style Questionnaire and the Emotional Resilience Questionnaire. Pearson’s correlation and Hayes PROCESS macro 3.5 model 6 were used in the mediating effect analysis. Results showed that positive coping style and resilience both buffered the negative effects of perceived stress on emotional, physical, and behavioral responses through direct or indirect pathways, and resilience had the strongest mediating effects. The findings urged relevant authorities and individuals to take measures to promote positive coping style and resilience to combat the ongoing pandemic stress and protect public physical and mental health.


Introduction
The recurring COVID-19 pandemic now constitutes a public health emergency of international concern despite being in its third year [1]. The outbreak and persistence of COVID-19 has brought a great burden to the public through the risk of infection, social isolation, economic downturn, and other negative events that put the public under great psychological stress [2][3][4]. Such chronic stress exposure can lead to various stress responses in individuals. Many studies confirmed that perceived stress [the evaluation of one's perceived level of stress] during the pandemic was positively relevant to individual emotional responses such as anxiety and depression [5,6], and physical responses such as insomnia [7], especially for those with psychic fragility [8]. According to the System-based Model of Stress proposed by Jiang [9], stress responses consist of emotional, physical and behavioral changes that people exhibit as a result of stress. However, no studies have yet explored the effects of perceived stress on different stress responses in the same group during the pandemic. Given the multidimensional nature of stress responses, a comprehensive study could provide a more systematic and holistic understanding of individual stress in the context of the ongoing COVID-19 pandemic. Individuals may exhibit different levels of perceived stress and stress responses even when confronted with the same stressors [10]. The Stress, Emotions, and Performance meta-model states that the stress process begins with the perception of stress, mediated by various levels of cognitive appraisal and coping resources, and then leads to positive or negative stress responses [11]. In this process, some protective or risk factors mediate the effects of perceived stress on stress responses. One of them is coping style. Coping style refers to an individual's cognitive or behavioral pattern in the face of frustration or stressors which can moderate the stages of stress as an individual trait [12]. Yan et al. [13] investigated the effect of coping style on the relationship between perceived stress and psychological distress and found that positive coping style alleviated individuals' emotional distress, while negative coping did the opposite. The results was consistent with most related-topic researches, with positive or adaptive coping being associated with lower levels of anxiety and depression, and negative or maladaptive coping exacerbating psychological distress of people [14][15][16]. Additionally, a review of stress-related mood disorders suggested that differences in coping styles directly leaded to differences in individual physiological responses to stressors, which in turn affected individual susceptibility to illness [17]. However, the role of coping styles in the relationship between perceived stress and physical or behavioral responses during the pandemic was still unclear.
Resilience is recognized as a pervasive individual characteristic that helps individual adapt to or overcome adversity, stress, trauma, and recover from these negative experiences [18,19]. Resilience has played an important role in reducing individual mental illness and protecting public well-being during COVID-19 [20][21][22][23]. Wilks and Croom [24] discovered that individuals with higher perceived stress may develop lower levels of resilience [25], which in turn resulted in higher psychological problems [26]. But similarly, there have been few studies on the role of resilience in mitigating the negative effects of perceived stress on physical and behavioral responses. As one of the important protective factors for stress, it is reasonable to speculate that resilience may also mitigate physical and behavioral stress responses of individuals during the pandemic.
Coping style and resilience are considered to be closely related concepts [27], which can jointly relieve individual stress responses. Campbell-Sills et al. [12] reported that coping style was significantly associated with resilience. Positive and adaptive coping style contributed to the development of resilience, while negative maladaptive coping style was an important risk factor for low levels of resilience [28]. A review from Shing et al. [29] also concluded that resilience during and after disasters may partly depend on individual coping style. Such ability to cope with stress was critical for people to recover and adapt after crises, which could be significantly strengthened by positive coping style [30,31]. To our knowledge, no researches have studied how coping style and resilience together function in the effects of perceived stress on stress responses.
In summary, this study aims to explore the effects of perceived stress on emotional, physical, and behavioral stress responses and the mediating roles of coping style and resilience in the Chinese population during the third year of COVID-19, in order to provide scientific suggestions for relevant organizations and individuals to take more effective measures to reduce stress responses and protect physical and mental health in the context of the ongoing pandemic. The proposed models of this study is shown in Fig 1.

Participants
Convenience sampling and snowball sampling were used in this study. A total of 1087 subjects were recruited to voluntarily participate in an anonymous questionnaire through the Questionnaire Star platform (https://www.wjx.cn/vm/YLUDsAO.aspx) from March 2022 to April 2022. The inclusion criteria included age above 18 years old, currently in mainland China, and voluntary investigation participation. The exclusion criteria included participants' ages of less than 18 or more than 70, participants response times of less than 200 s or more than 1800 s, repetitive answers, and confusing logic. Finally, 873 valid respondents were included in the analysis (valid ratio = 80.31%, mean age = 38.22 ± 11.95), from 89 cities in 28 provinces of China.
This study was approved by the Ethics Committee of Naval Medical University (NMU-MEREC-2021-043). The ethical principles of the Declaration of Helsinki were followed in the course of the study. All participants were asked to complete an informed consent notification prior to the questionnaire. Furthermore, participants were guaranteed the voluntary and confidential of their responses and their rights to quit the survey at any time.

Demographics.
Demographic variables included gender (Male, Female), age (18-35, 36-50, >50), occupations (Occupations with COVID-19 exposure risk: healthcare works, administrators whose work is directly involved with the pandemic, pandemic volunteers, etc; Occupations without COVID-19 exposure risk: enterprise worker, teachers, students, etc), quarantine or not (Being quarantined, Not being quarantined), and financial worries (Extreme worry, Serious worry, Moderate worry, Mild worry, Not at all.) 2.2.2 Perceived stress. The Perceived Stress Scale (PSS-10) was applied to measure to which degree people felt their lives as stressful in the past month [32]. The scale consists of 10 items ranged from 0 (never) to 4 (always). The total scores are calculated by the sum of the 10 items ranging from 0 to 40. Higher scores denote higher perceived stress. In this study, the Cronbach's α was 0.834.

Stress responses.
The 28-item Stress Response Questionnaire [9] was used to assess the degree of individual's stress responses over the last month. The scale includes three subscales: Emotional Response (ER: anxiety, depression, anger, etc. i.e.,"Feeling sullen and depressed."), Physical Response (PR: dizziness, body pain, fatigue and lassitude, etc. i.e., "Feeling weak and tired easily."), and Behavioral Response (BR: avoidance, reduced physical activity, etc. i.e., "Too lazy to move."). Each item is scored on a 5-point Likert scale from 1 (surely yes) to 5 (surely not). The total scores for each subscale are summed by the corresponding items. Only three subscales were used in the present study and the Cronbach's α for ER, PR and BR was 0.946, 0.915 and 0.847, respectively.

Coping style. The Simplified
Coping Style Questionnaire (SCSQ) was employed to measure the coping style (CS) that people were accustomed to using in their lives [33]. There are two dimensions of this scale: positive coping style with 12 items and negative coping style with 8 items. Items are rated on 4-point Likert scales from 0 (never) to 3 (always). In this study, the participants' final coping style scores were equal to the positive coping scores minus the negative coping scores. The higher the final score, the more inclined the individual was to the positive coping style, and the less inclined the individual was to the negative coping style [15]. The Cronbach's α was 0.876 for the current study.

Resilience.
The Emotional Resilience Questionnaire (ERQ) was selected to measure resilience (R). This scale was firstly designed by Zhang and Lu [34] based on Chinese local culture to assess the resilience of adolescents, the validity has also been demonstrated in adults [35]. The questionnaire includes 11 items rated from 0 (never) to 6 (always). The total scores are the sum of the 11 items with higher scores indicating greater resilience. The Cronbach's α was 0.845 in this study.

Data analysis
All data were analyzed by SPSS21.0 (IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp). Descriptive statistics were conducted to describe demographic characteristics. Pearson's correlation analyses were used to examine the correlation between variables of interest. Model 6 of PROCESS v 3.5 was selected to test the mediating effects of coping style and resilience [36], and the significance of indirect effects were examined by bootstrap method (5000 bootstrap samples) with 95% confidence intervals (CIs). Demographic characteristics were included in all mediation models as covariates. All variables were standardized before analysis. All statistical tests were two-tailed with p < 0.05 as statistically significant.

Sample characteristics
The sample characteristics are presented in Table 1. More than two-third of the participants were female (63.80%). 48.45% of the samples were aged between 18-35, and 35.51% were 36-50. 24.74% were occupationally at the risk of COVID-19 exposure. About half of the participants were being quarantined at the time of our investigation. 6.99% of the individuals reported extremely worried about self finances and 20.39% didn't worried at all. Table 2 shows the results of Person correlation analysis between variables. Perceives stress, emotional response, physical response, and behavioral response were positively inter-correlated with each other, and were all negatively associated with coping style and resilience (all p < 0.01). Coping style was positively related to resilience (p < 0.01).
The bootstrap method mediating analysis (

Discussion
COVID-19 posed a widespread and extensive threat to the public as a worldwide health emergency. The persistence of such a negative stressor would trigger a range of psychological, physiological and behavioral changes of people [37]. This study provided a comprehensive perspective about the effects of perceived stress on emotional, physical, and behavioral stress responses, as well as the separate mediating and co-mediating effects of coping style and resilience. As expected, perceived stress was positively associated with emotional, physical, and behavioral responses. People with higher perceived stress reported more negative emotions, more severe physical symptoms, and more maladaptive behaviors, which was in line with most of the previous studies [38 -41].
In the present study, coping style alone mediated the association between perceived stress and behavioral responses, and positive coping could buffer the negative effects of perceived stress on behavioral responses. However, coping style did not mediate the effects of perceived stress on emotional or physical responses, which was inconsistent with previous studies. A majority of studies regarded coping style as an important stress mediator between stressors and all kinds of stress responses [42,43]. People who prefer positive coping style tend to face problems directly and take ways to solve it positively, while people with negative coping style are inclined to avoid problems by denying and withdrawing, which in turn leads to worsening of emotional responses such as anxiety and depression, and an increase in physical responses such as lowered immunity [13,17,44]. Here are three possible explanations for the inconsistency. One is that the method of calculating coping style in our study may weaken the effects of different coping styles, since positive and negative coping styles have opposite effects. Another is that coping styles themselves are behavioral expressions and thus have stronger influence on behavioral response. The third explanation is that the role of coping style in the effects of perceived stress on emotional and physical responses are complicated. An mediation research conducted in older people reported that neither positive nor negative coping was correlated with anxiety response [45]. Lau et al. [14] also discovered that coping style did not have a direct effect on anxiety, but negative coping style showed a positive and significant effect on anxiety after positive coping style was added as a moderating variable to the structural equation. Therefore, the function of coping style in stress process still needs further research. The results demonstrated the mediating role of resilience in the relationship between perceived stress and stress responses. Consistent with previous research, higher perceived stress was associated with lower levels of resilience, as the ongoing stress from the epidemic increased the burden on people's coping resources [46]. And higher resilience was associated with less stress responses [26, 47,48]. More importantly, our study confirms the role of resilience in buffering physical and behavioral responses in addition to emotional responses. As an effective protective factor, the higher the level of individual resilience, the better the individual's ability to counteract perceived stress and the less emotional, physical, and behavioral stress responses are exhibited. According to the Stress Inoculation theory, moderate stress exposure contributes to resilience development. Some longitudinal studies also found that the psychological problems of individuals increased sharply in the early stages of the pandemic, then decreased rapidly, which was interpreted as the stimulation and validation of resilience [49,50]. However, longer term longitudinal studies are needed to clarify whether individual coping resources and resilience will be depleted as the pandemic continues. In any case, at least in the third year of the COVID-19 pandemic, resilience still plays an important role in mitigating various stress responses of people.
Coping style and resilience showed chain mediating effects between perceived stress and emotional, physical, behavioral responses in the current study. Many studies endorsed that people with fewer psychological problems in the pandemic had more successful coping and higher levels of resilience [51,52]. As a resilience protective factor, positive coping style was proved to contribute to resilience [12,28,30]. Except for behavioral response, coping style in this study cannot directly affect the individual's emotional and physical responses, but need to be through resilience, and the more positive the coping tendency, the higher the resilience and the less the individual's emotional, physical, and behavioral responses. As for the mediating effect size, the mediating effect of resilience was the strongest among all indirect pathways, suggesting that resilience performed a stronger role in buffering the effects of perceived stress on stress responses. In contrast, the simple mediation of coping style and chain mediation effects of coping style and resilience were weaker. Nevertheless, our study establishes the important roles and pathways of coping style and resilience in the relationship between perceived stress and different stress responses. The results suggest that fostering positive coping style and promoting resilience are necessary for individuals to better adapt to pandemicrelated stressors, reduce stress responses, and recover quickly from pandemic trauma. Individuals are encouraged to proactively develop available protective measures, such as learning stress management methods [36], doing physical exercise or maintaining healthy lifestyle [53], and cultivating meaningful relationships for social support [54,55]. Governments and mental health organizations already have some useful measures, such as encouraging social connections [56], organizing psychological support groups, and providing services for mindfulness practice [57]. Some coping-focused efforts like coping skills training courses and online virtual stress adaptation training may also be helpful as our results have verified the positive effect of coping style on resilience [58,59].

Limitation
Some limitations should be considered when interpreting the results of this study. Firstly, the convenience and snowball sampling used in the study may affect the generalization of the results and the representativeness of the sample, even though our sample was distributed across the majority of Chinese provinces. And as a cross-sectional study, no causal conclusions can be inferred. Secondly, several demographic variables (such as gender, age, and economy) were selected as covariates to increase the reliability of the results, but the factors influencing the dependent variables are actually numerous and complex. Except for demographic influences, social or political factors may also affect the perceived stress and stress responses of people. Thirdly, this study focused only on the mediating role of coping style and did not explore the effects of specific coping strategies. Studies have shown that positive or negative coping strategies did not necessarily alleviate or exacerbate stress responses. For example, Panourgia et al. [60] discovered that avoidance behavior can be an effective adaptive strategy in some situations, allowing people to deal with problems more quickly. Considering the complexity of the effects of coping, the ways in which coping and specific coping strategies function deserve further study. Fourthly, the present study explored emotional, physical, and behavioral stress responses in general but not in depth, and future studies could examine each stress response type in more detail. Last but not least, this study included the variable of "quanantine or not" as a covariate, but some studies showed that quarantined people experienced higher levels of stress [61,62], which means that some quarantined participants in this study may have reported higher levels of perceived stress and stress responses, so the findings may be biased and should be interpreted with caution. Further studies could continue to explore perceived stress and stress response of individuals in different quarantine states, as well as the influencing factors.

Conclusions
This study is the first to examine overall the effects of perceived stress on emotional, physical, and behavioral responses and the mediating roles of coping style and resilience during the recurrent outbreak of the COVID-19. The results indicated that more positive coping style and especially higher levels of resilience buffered the negative effects of perceived stress on different stress responses, suggesting that relevant authorities and individuals should take measures to foster positive coping and promote the development of resilience to against the ongoing pandemic stress and to protect individuals' physical and mental health.